The use of surgical drapes in operating theaters is well established. Drapes are employed to cover, and to separate, non-sterile objects (for example, the non-sterile parts of a patient's body) from the sterile environment of the operating theatre and the operating theatre staff, and are available in many different shapes and constructions, depending on the nature of the surgical procedure that is being carried out. Increasingly, drapes are intended for a single use only and are supplied to users already sterilized, in sterile packaging. Usually, it is necessary for the drapes to be folded so that the packages are of a convenient shape and size and it is then necessary to ensure that, in the operating theatre, it is possible to unfold and place the drape in position without contaminating the outer surface of the drape material (e.g., in the case of a patient drape, the surface remote from the patient's body and, in the case of a table drape, the surface remote from the surface of the table). In other words, it is necessary to ensure that the drape can be unfolded and placed in position without the outer surface of the drape material coming into contact with non-sterile objects (for example, the patient's body) because the surface will then no longer be aseptic (uncontaminated). It is also desirable that it should be possible to unfold and position a drape quickly and easily, to avoid introducing delays.
Sheet drapes, comprising rectangles of drape material, are widely used during surgical procedures for covering areas of the patient's body and also for covering flat surfaces (e.g. instrument tables) in the operating theatre. Sheet drapes are available in a wide range of sizes and the larger sizes can present particular problems both for the supplier, in that they have to be folded many times before they are of a convenient size for packaging, and for the user, in that they have to be handled carefully to avoid contamination.
The importance of the way in which drapes are folded is well recognised, and various ways of folding particular drapes have been proposed. One known way of folding sheet drapes comprises fan-folding the drape in the longitudinal direction from the ends to the middle, forming an elongated multi-layer strip, and then in the transverse direction from the sides (now the ends of the multi-layer strip) to the middle. The result is two side-by-side stacks of fan-folded material, each having a respective edge of the drape on top and joined at the bottom by a bridging portion. The bridging portion is then folded in half, to form a single stack of folded material with the bridging portion on the outside faces.
A sheet drape which has been folded by that method is compact and, from the point of view of a drape supplier, has the advantage that it is very suitable for packaging. The folding method has the disadvantage, however, that a comparatively large number of steps are involved in fan-folding the drape in the two directions. From the point of view of the user there is the advantage that, when the bridging portion has been unfolded to reveal the two side-by-side stacks of folded material, the side edges of the drape are immediately accessible for unfolding the drape in a comparatively simple manner. The need to unfold the bridging portion first can, however, present problems since it requires the user to locate the center of the single stack formation in which the drape is supplied. In addition, if there are a comparatively large number of fan-folds to be undone, it can be difficult for the user (especially when working single-handed) to control the drape during the unfolding operation.
Various methods of folding sheet drapes, or other drapes having a sheet-like form, are described in U.S. Pat. Nos. 3,343,534; 3,537,446; 3,721,234; 4,051,845; 4,164,941; 4,553,539; and 4,627,427.